1. Field of the Invention
This invention relates to a power supply unit and a connector connection failure detection method, and is applicable to a vehicle power supply unit for supplying power from a battery or an alternator via a wire harness to loads of head lights, etc., for example.
2. Description of the Related Art
Conventional power supply to loads of a vehicle is executed according to a configuration as shown in FIG. 5. The configuration in FIG. 5 will be discussed. Power from a power supply section 1 of a battery, an alternator, or the like is supplied to an output driver 2 made of a semiconductor switch, etc. The output driver 2 is controlled based on a control signal S1 from a CPU (central processing unit) 3. When the control signal S1 is positive logic, the output driver 2 outputs power supplied from the power supply section 1 to a power supply line 4.
Here, the CPU 3 receives time division data such as ignition switch information and vehicle state information from another control unit installed in the vehicle over multiple signal lines 5 and generates the control signal S1 based on the data. The CPU 3 and the output driver 2 are installed on a single circuit board 6 placed in a junction box.
A circuit board connector 7 formed in the circuit board 6 is joined to a harness connector 9 formed at one end of a harness 8, whereby the power supply line 4 is electrically connected to a load 10 via the connectors 7 and 9 and the harness 8 and thus power is supplied to the load 10.
In this connection, in fact, a plurality of output drivers 2 corresponding to a plurality of loads are disposed in the circuit board 6. Therefore, a plurality of power supply lines 4 from the output drivers 2 are introduced into the circuit board connector 7. Likewise, the harness 8 formed with the harness connector 9 comprises a bundle of power supply lines connected to a plurality of loads 10.
If connection of the circuit board connector 7 and the harness connector 9 is incomplete, there is a fear of occurrence of an arc based on a connection failure between a terminal 7A of the circuit board connector 7 and a terminal 9A of the harness connector 9. Reliability of power supply lowers and if various conditions overlap, it is also feared that an arc may cause a vehicle fire in the worst case.
In this connection, such a connector connection failure is caused by a connector insertion mistake of a worker or vibration when the vehicle runs.